Its probably been asked before but i could not find much information, i serviced a Tilley Guardsman earlier, performed a dunk test and it passed without issue, it lit fine, it is internally clean, doesn't look overly used and was eventually quite bright, i forgot to count how many pumps i gave it, it must have been at least fifty to sixty before the pressure pip was level with its holder but it didn't take long before it started to pulse a little so i gave it another twenty or so which made it run smoothly but not for too long as it needed a few more, i'm sure i've read that some lanterns need around a hundred pumps.
1. The number of "pumps" required to operate a 'standard' lantern will vary with a number of factors including the efficiency of the pump, the size of the tank, and the amount of fuel/airspace in the tank. 2. The Tilley pressure pip may not always work correctly. A long time ago I was told that if the pressure pip emerges from its housing before 100 pumps on a full tank, it should be filed flat to the surface of the pip tube. My view is the pressure pip is an indicator, not a meter. Herman Lahde in "Light and Heat from Hydrocarbon Appliances" (2000) says that the standard operating pressure (of Petromax lamps) "...is practically always from 25 to 30 lbs per square inch (or 1 3/4 to 2 atmospheres). While it is possible to use a higher operating pressure, this is not done and today's lanterns are built for standard pressure". Cheers Tony
Thanks Tony, The tank was filled to around an inch below the fuel filler, the nrv has a new pip, nos spring, new pump leather fitted and seemed to work well, For sure and being nearly seventy it is entitled to be a little less accurate, on Basecamps Tilley instructions page he states that they rarely work although i find most to be fine with the lanterns running well, i will give it another run tonight and count properly this time, its a gift for a friend with no experience of pressure lamps, i guess in some instances it would be nice to have an accurate pressure gauge for situations like this.
With a Tilley fill with 1.5 imperial pints (30floz) and then 100 pump strokes. That should get the pressure to about 2 bar or 28-30psi which is the correct operating pressure for the 300cp Tilley. ::Neil::
I do believe that anything from one to two bar should power any lantern well. If it needs higher pressure to stop pulsing it may be that the vaporiser is a bit choked up or there is a bit of carbon moving about in it.
There are some E41 lanterns in the gallery that have gauges, with a red line at the 30 psi mark halfway on the dial .. for me, that would indicate that 30 psi is the correct working pressure for these and probably all Willis & Bates lanterns?
@Mackburner Thanks Neil, i will make a note of that but doubt i'll be trying it on any B's just in case, @Fireexit1 I did my usual tapping out of loose carbon until there seemed to be no more and operated the cleaning needle a few times but there wasn't any improvement, @podbros That does sound correct, i have only had a couple of cases like this in the four or five years of collecting, most lanterns etc are good at around forty pumps in my experience,
Well that 1.5 pints and a hundred pump strokes is in the instructions for the X246B. I did check it some years ago with a pressure gauge fitted to the valve and it does give around 2 Bar. I agree probably best not to go that far BUT in the instructions for the 500 series they state 150 pump strokes which I ragard as stupidly excessive for that B type tank. However the numbers do give an effective method to check the pressure pip on the older lamps and allow you to "Re-set" the gauge by filing down the rod to level it. ::Neil::
I think it must have been one of your posts that i read a while back saying the same but i couldn't find it this time, maybe they were a little stronger when new but as you say a little dodgy nowadays, i, like most of us no doubt, have come across many over pressurised A's and B's and a few RH57's but not too many of the earlier models in comparison, i think my arm would fall off after 150 pump strokes! I need to buy a "Paraffin" jug so that i can get a correct measurement and then re set the gauge, Thanks Neil.
Generally speaking, the term 'pressure' has nothing to do with the number of pump strokes. The number of strokes corresponds to the volumetric displacement of air from the pump into the fount. The more air you get into a fixed volume within the fount, the greater the force exerted by it over an area. That is because air is compressible and thus, a greater amount of air can occupy a fixed volume. In this case, more air molecules would be exerting a greater force over or against the same area (fount's inner wall or the area on the surface of the fuel pool). That greater force over the same area would be equal to higher 'pressure'. Some lanterns need more(higher) pressures than others in order to maintain the required fuel flowrates through the jet's orifice so that the burning-rates produce the required amount of thermal energies for conversion into their respective rated light outputs. Of course, that only applies if the rate of fuel vaporization by the generator is proportional to the fuel flowrate. Otherwise, you'd be getting liquid fuel into the mantles.
Well the 1.5 pints is roughly 10 - 15mm over the level that i have been filling so not too bad but would still need a fair bit more pressure to be at the correct amount and why i never bought a jug in the first place to fill things with i'll never know Thanks for the information MYN, interesting stuff.
I don't put any faith in the pressure pip. Some work, most don't. I pressurise until there's an even light output and then give it a few more pumps for luck. It could be 15, it could be 30, I don't count, I go by performance Its based on the shape of the fount, height of the burner (column of fuel), volume/efficiency of the vapouriser and length/shape of the air/vapour tubes. Alec. PS I hate over pumping very old lanterns/stoves, got to show the old beasties respect and sympathy
I normally give around forty to fifty pumps for the dunk test and similarly for the majority of lanterns to get a good steady light but as previously said i have had a handful that would just pulse without near double that amount, but of those i am always dubious as to whether damage could be caused whilst giving them the extra pressure although touch wood, so far so good.
Pressure pips can be tricky… some work and some don’t. I give the lantern about 30 pumps and start it. If it’s dim (much like me) then give it some more pumps until it’s running the way you want it to. All the lanterns I have that have pips work(!). Lucky, I guess but I still don’t completely trust them.
In order to reduce the tendency to pulse, there is a certain pressure range that has to be maintained or exceeded in the fount of an operating pressure lamp, lantern or stove so that:- 1. there is sufficient resistance against 'back pressures towards the fount' created by the tendency of the heated fuel in the generator to expand in all directions. 2. to maintain a pressure gradient so that the fuel flowrate through the jet orifice doesn't fall below a norminal level where the rate of vaporization could easily exceed. This is a little more complex as there are more than a few factors that could contribute to it and is closely related to reason no. 1 above. We should be aware that the fuel will rise and completely fill/occupy all free spaces within the generator as long as the gen is opened at one end(jet orifice) the pressure in the fount is sufficient to overcome the head created by the height of the gen and the atmospheric pressure outside. If burning rate at the mantle could result in sufficient heat being released and absorbed by the gen and its contents, the fixed volume of fuel in the gen will tend to expand in all directions. This area becomes sort of a pressure source. If the difference in pressure between the fount and this 'new' pressure source becomes zero or negative, pulsing would be initiated. If the effective volume occupied by liquid fuel in the generator is lower than standard, the tendency to pulse also becomes lower. That is because there will be less pressure created by a lesser amount of fuel tending to expand when heated.
Well i took the gift lantern to my friends house today and thought i would show him how to use it and guess what, it wouldn't light, i traced it to not being able to build pressure, the culprit, the newly acquired and fitted non return valve pip from a well known ebay seller, it had swelled up to twice its normal size and wouldn't let hardly any air past it, obviously it must have been a poor quality rubber to swell up in such a short time and must have started swelling straight away, i have never previously had any issues with his pips before, anyway after tidying it up with a sharp blade (another will be fitted) the lantern worked perfectly and only needed around forty pumps to run properly, sadly all of the other pips from that batch were added to the others i have in stock, maybe i should soak all of them in fuel to see which ones swell?
Either way, not fit for purpose on this occasion, i have not had any trouble with any of his others so far.
@MG I bought a bunch of brass cups with rubber pips that all went to mush in kerosene and naphtha — I tested them before use. I stock up with pips from The Fettle Box: always good quality; and I have spare Viton sheet. Cheers Tony
@Tony Press Likewise, i have been buying the nos brass cups with springs, i have found it quite difficult in the past to get a good nrv seal with Viton pips as it can be too hard, i use it for other seals but i prefer the rubber ones on Tilley's and have been using them for a few years now, this is the first problem i have had with them, i still have plenty of Viton pips so will probably fit one this time, if it seals first time i may start to use them again.
I’ve never had the issue of the Viton pips from The Fettle Box being “too hard”; nor from my Viton sheets. Cheers Tony
It was a while back so i'll give them another try, i have a couple of sheets of Viton and some punches but so far have only used them for one pump cap washer on a blow torch, i definitely replace the nrv springs with nos on each Tilley lantern as a matter of course these days as quite often the originals were too weak.
Two different Viton pips, the second i turned around, had to "seat" it and then had to stretch the nos spring but finally it looks like its sealed, the rubber ones definitely seal easier and without needing to stretch the spring, well for me at least anyway.
The Viton sheet I'm having has a durometer hardness of around 75 Shore A. I find it too hard to be used as pip material for most lanterns or stoves. I'd prefer something as soft as most silicone rubbers but these silicones are not fuel resistant. Buna-N (nitrile/NBR) is ok. In most instances, I just use old-fashioned cork.
I just find it easier to buy Viton service kits so am not sure what hardness they are, i have bought and used many of the rubber Tilley pips without issue but do know there could be nine non fuel resistant ones in amongst the stock of good ones that i have previously bought, i'd best soak them to sort out the bad ones, I have only come across a handful of stoves etc fitted with their original cork pips.
Like others here I bought Tilley cups instread of using the later design solid rubber seal. I usually replace the rubber with Viton ones from the fettlebox. I did have issues with the new Tilley SP1 springs being too powerful and not allowing air into the tank. But as you say - the rubber swelling up in paraffin marks it out as "useless". I hope that your vendor will make good - and suspect that he has inadvertently used the wrong material or himself has been misled so would probably want to hear of this.
The trouble is i can get a bit impatient, i service quite a lot of lamps sometimes and when i kept having problems with the Tilley Viton pips (Vapalux usually work first time) i tried those from a different seller, this is the only one i have had trouble with in at least a year, probably quite a bit longer, I have made him aware although i doubt i'll here anything back, his nos springs are well worth buying and i have stocked up on those to, again if i stretch a Vapalux spring it works fine but have struggled with the Tilley ones being too weak.
My deduction is that the red line means maximum pressure, optimum operating pressure should be lower.
Your deduction should be that liquid hydrocarbon pressure lamps and lanterns operate most efficiently between 25 and 30 psi. As per my response elsewhere where you’ve raised this point. Tony
